The 8520-CPUX is a CPU module, manufactured by Allen Bradley Inc. This Central Processing Unit belongs to the 9/260 series product line of modules by Allen Bradley. The 8520-CPUX board can be found with two alternative part numbers, which 90781002 for the revision 02, or 90781001 for the 01 revision.  With a weight of approximately 3 pounds (1.36 kilograms) and dimensions close to 16 x 11 x 3 inches (406.4 x 279.4 x 76.2 millimeters), this Industrial Control System unit is one member of a series of parts that are necessary for the functionality of a 9/260 type enclosure. This processing unit, the 8520-CPUX, should be paired with a Motherboard and the Main Power Supply (abbreviated PS1). All three of these units will have to be inserted into the 9/260 series enclosure housing. The enclosure for which this CPU is necessary is a type of enclosure that can support digital or analog servo modules. This enclosure also supports remote I/O ports and the main power supply. When installing all of the necessary components to operate the 9/260 (or 9/290) type enclosure, the motherboard unit should be installed first and attached to the rear enclosure wall. This CPU can then be inserted next to the motherboard and attached to it. This CPU board should be slid along the provided tracks when removing or inserting it, to ensure that it is installed or removed correctly. This board contains a green LED light which has various indication abilities and an RS-232 port (port A), both of which can be seen when viewing the module from its front view. (The port on this part is used for RS-232 type communications only). From the side, the user will be able to see this CPU’s high-speed shadow RAM, its EPPS Jumper, its Super Capacitor, and its Flash memory on SIMMA.